traffic-signal.md

Designing a Traffic Signal Control System

In this article, we will explore the object-oriented design and implementation of a Traffic Signal Control System using Java.

This system is crucial for managing traffic flow and ensuring safety at intersections.

System Requirements

The Traffic Signal Control System should:

1. Signal Timing Management: Control the timing of traffic lights.
2. Intersection Management: Manage multiple traffic signals at an intersection.
3. Mode Configuration: Support different traffic modes.
4. Emergency Override: Allow manual control in emergencies.

Core Use Cases

1. Switching Signals: Change signals from red to green and vice versa.
2. Timing Adjustment: Modify the duration of each signal.
3. Mode Selection: Choose operational modes.
4. Emergency Control: Manual override for emergencies.

Key Classes:

• TrafficSignalSystem: Manages the system.
• TrafficLight: Represents an individual traffic light.
• IntersectionController: Manages lights at an intersection.
• ControlPanel: For manual control and emergency overrides.

Java Implementation

TrafficLight Class

Represents an individual traffic light.

public class TrafficLight {
    private String id;
    private LightState state;

    public TrafficLight(String id) {
        this.id = id;
        this.state = LightState.RED;
    }

    public void changeState(LightState state) {
        this.state = state;
    }

    // Getters and setters...
}

enum LightState {
    RED, GREEN, YELLOW
}

IntersectionController Class

Manages traffic lights at an intersection.

import java.util.HashMap;
import java.util.Map;

public class IntersectionController {
    private Map<String, TrafficLight> trafficLights;

    public IntersectionController() {
        this.trafficLights = new HashMap<>();
    }

    public void addTrafficLight(TrafficLight light) {
        trafficLights.put(light.getId(), light);
    }

    public void changeSignal(String lightId, LightState state) {
        if (trafficLights.containsKey(lightId)) {
            trafficLights.get(lightId).changeState(state);
        }
    }

    // Additional methods...
}

ControlPanel Class

For manual control and emergencies.

public class ControlPanel {
    private IntersectionController controller;

    public ControlPanel(IntersectionController controller) {
        this.controller = controller;
    }

    public void overrideSignal(String lightId, LightState state) {
        controller.changeSignal(lightId, state);
    }

    // Additional methods...
}

TrafficSignalSystem Class

Main class managing the traffic signal system.

import java.util.ArrayList;
import java.util.List;

public class TrafficSignalSystem {
    private List<IntersectionController> intersectionControllers;

    public TrafficSignalSystem() {
        this.intersectionControllers = new ArrayList<>();
    }

    public void addIntersectionController(IntersectionController controller) {
        intersectionControllers.add(controller);
    }

    // Methods to update system configurations...
}